Apparatus for settling turbid liquid



May 27, 1941. B, SOFFE 2,243,582

APPARATUS FOR SETTLING TURBID LIQUID Filed Aug. 3, 1939 BENJAMIN F.SOFFE'.

INVENTOR.

A TTORNEY Patentecl May 27, 1941 2,243,582 APPARATUS FOR SETTLI N GTURBID LIQUID Benjamin F. Sofle, Detroit, Mich.

Application August 3, 1939, Serial No. 288,067

2 Claims.

This invention relates to apparatus for settling turbid liquid; and itcomprises a settling tank having a conical bottom, an inlet for liquidnear the top of the tank, a sludge outlet at the bottom of the tank, anda plurality of co-axial, closely spaced uptake funnels discharging intoa common outlet for settled liquids; all as more fully describedhereinafter and as claimed.

In the settling of turbid liquids it is customary to employ a tank whichhas a conical uptake in its lower portion. The turbid liquid is admittedat the top of the tank. As the liquid slowly flows downward, settlingtakes place. The settled liquid flows through the uptake to a point ofuse while the sludge is collected on the bottom of the tank whence it isremoved from time to time. In such arrangement the settled liquid isrequired to turn sharply around the lower edge of the uptake so that itsvelocity is greatly increased. This results in a tendency to carryturbidity along so that the settled efiiuent is not as clear as isdesirable.

In softening water by hot lime-soda treatment, for instance, the slightturbidity remaining in the settled water is further reduced by passagethrough filters. The filters are backwashed periodically to remove thecollected sludge, and this backwashing is carried out with settledwater. During backwashing the rate of flow through the uptake isincreased, resulting in an increased velocity around the edge of theuptake and thus in an appreciable but undesirable increase in turbidity.

It is an object of my invention to provide an apparatus in which thevelocity of the settled liquid passing into the uptake is greatlyreduced to result in a clearer eiiluent.

Another object of my invention is to provide an apparatus which permitsa temporary increase in the rate of withdrawal of settled liquid Withoutappreciable increase in turbidity.

The manner in which these objects are achieved is illustrated in theappended drawing, in which Fig. 1 is a sectional elevation, more or lessdiagrammatic, of an apparatus according to my invention; and

Fig. 2 is a modification of the apparatus of Fig. 1.

Similar reference numerals refer to similar parts throughout the severalviews.

Referring now to Fig. 1, a settling tank H] has a conical bottomprovided with a valved sludge outlet I2. The top i3 of the tank carriesa water inlet chamber l4 having a water inlet and spray heads l6discharging into a steam space H in the upper portion of the tank. Aninlet is for chemicals, e. g. lime and soda solution, discharges intothe steam space I! adjacent to the spray heads I6. The steam space H isprovided with a steam inlet I9 and a valved vent 20.

In the lower part of tank H] are three closely spaced uptake funnels,2|, 22 and 23 which are connected with concentric tubular members 30, 3|and 32, respectively. The outermost member 32, provided with a closedtop 33, is longer than members 3| and 32, and is connected with anoutlet 27 for settled water. The diameter of the tunnels isadvantageously of the order of 10 per cent of the diameter of tank l0 sothat the funnels occupy approximately half the cross sectional area oftank It. The angle between the sides of funnels 2| to 23 and thehorizontal should be not less than the angle of repose of the sludgeprecipitated in tank It), usually 45 to degrees.

Operation of the apparatus shown in Fig. 1 is as follows. Water enteringthrough inlet l5 and chamber I4 is discharged by spray heads l6 into thesteam space I! in a fine shower. -It is heated by contact with steamentering through inlet l9, and mixed with chemicals entering throughinlet l8. Any gases dissolved in the water and released in the heatingthereof are discharged through vent 23. As the water flows slowlydownward in the tank I3 reaction with the chemicals takes place.Precipitates form and move downward, collecting as sludge 28 on theconical bottom II. This sludge is removed at intervals through sludgeoutlet Ill. The clarified water passes into funnels 2|, 22 and 23 asindicated by the arrows and thence flows through the concentric tubularmembers 30, 3| and 32 to outlet 21.

In Fig. 2 there are but two funnels 2| and 22. The apex of funnel 2|connects with a short tubular member 35. The apex of funnel 22 connectswith a larger concentric tubular member 36 of such length as to reachinto steam space H. Within member 33 is a foraminous steam chest 31supplied with steam through inlet l9. Above the steam chest 31 thetubular member 36 expands into achamber 38 which is in communicationwith outlet 21. The open top of member 36 is protected by a hood 39which prevents the entering of raw water or chemical. In operation,settled liquid enters the funnels 2| and 22 as shown by the arrows andpasses upwardly through tubular members 35 and 36. Steam emerging fromsteam chest 3'! bubbles up through the clarified water, and by agitationand dilution reduces further the dissolved gases entrained in the water.The clarified and deaerated water leaves through outlet 21, while thesteam passes through the open top of member 36 into the steam space H,there to heat the incoming water.

While I have described my invention with particular reference to hotprocess lime-soda softening of water, it may, of course, be employed inother processes involving clarification of turbid liquids, such as fruitor sugar juices, etc.

As compared with a single funnel, the use of two funnels shown in Fig. 2reduces the velocity around the edges of the funnels to one-half, whilethe use of three funnels as shown in Fig. 1 reduces it to one-third.Where a further reduction in velocity with correspondingly greaterclarity of efliuent is desired a greater number of vertically spacedfunnels may be employed. Other modifications will occur to those skilledin the art without departing from the spirit of my invention, andreference is, therefore, made to the following claims for a definitionof the scope of my invention.

I claim:

1. In apparatus for settling turbid liquid comprising a settling tankhaving a bottom, a. liquid inlet at the top of the tank, and a sludgeoutlet at the bottom, improved means for withdrawing settled liquid fromthe tank comprising a plurality of co-axial, vertically spaced uptakefunnels in the lower portion of the tank, a plurality of concentricvertical tubular members, the innermost tubular member terminating inthe apex of the lowermost funnel, the outermost tubular memberterminating in the apex of the uppermost funnel and extending to ahigher elevation than any other tubular member, and a liquid outlet forthe tank communicating with the outermost tubular member.

2. In apparatus for settling turbid liquid comprising a settling tankhaving a bottom, a sludge outlet at the bottom, and a steam space and aliquid inlet at the top of the tank, improved means for withdrawingsettled liquid from the tank compising a plurality of co-axial,vertically spaced uptake funnels in the lower portion of the tank, aplurality of concentric vertical tubular members, the innermost tubularmember terminating in the apex of the lowermost funnel, the outermosttubular member terminating in the apex of the uppermost funnel and beingin free communication with the steam space, steam distributing means insaid outermost tubular memher, and a liquid outlet in communication withsaid outermost tubular member between the steam distributing means andthe steam space.

BENJAMIN F. SOFFE.

